Synthesis Of Metal Nanoparticles Research Articles

Bacterial synthesis of metal nanoparticles as antimicrobials.

Nanoscience, a pivotal field spanning multiple industries, including healthcare, focuses on nanomaterials characterized by their dimensions. These materials are synthesized through conventional chemical and physical methods, often involving costly and energy-intensive processes. Alternatively, biogenic synthesis using bacteria, fungi, or plant extracts offers a potentially sustainable and non-toxic approach for producing metal-based nanoparticles (NP). This eco-friendly synthesis approach not only reduces environmental impact but also enhances features of NP production due to the unique biochemistry of the biological systems. Recent advancements have shown that along with chemically synthesized NPs, biogenic NPs possess significant antimicrobial properties. The inherent biochemistry of bacteria enables the efficient conversion of metal salts into NPs through reduction processes, which are further stabilized by biomolecular capping layers that improve biocompatibility and functional properties. This mini review explores the use of bacteria to produce NPs with antimicrobial activities. Microbial technologies to produce NP antimicrobials have considerable potential to help address the antimicrobial resistance crisis, thus addressing critical health issues aligned with the United Nations Sustainability Goal #3 of good health and well-being.

Biosynthesis and characterization of gold nanoparticles from citrullus colocynthis (L.) schrad pulp ethanolic extract: Their cytotoxic, genotoxic, apoptotic, and antioxidant activities

The age-old discipline of plant therapy has gained renewed importance through the utilization of plants for the synthesis of metal nanoparticles. However, toxicity testing and characterization of the recently synthesized nanomaterials are essential to evaluating their appropriate application. Citrullus colocynthis is a medicinal plant with several health benefits. Herein, we used its ethanolic pulp extract (PE) to manufacture gold nanoparticles (PE-AuNPs). Various approaches were employed to assess the MTT50 and NR50 values of PE and PE-AuNPs at different concentrations in the human hepatocarcinoma cell line (HepG2). The study aimed to assess the genotoxic effects and in vivo toxicity of PE and PE-AuNPs at MTT50 dosages. The quasi-spherical, cubic/triangular prisms, and nail-looking particles exhibited no antioxidant properties. They had an absorbance peak between 540 and 560 nm, diameters of less than 20 nm, hydrodynamic diameters of 177.9 nm, and a negative surface charge (−10.3 mV). The significant role of plant phytochemicals in the formation of metal nanoparticles is confirmed by the diminished antioxidant capacity of extract residues following PE-AuNP synthesis. PE-AuNPs exhibited in vivo and cytotoxic effects at relatively lower concentrations compared to PE. In contrast to PE, PE-AuNPs exhibited lower genotoxic at MTT50 dosages. Despite having MTT50 values of approximately 1.95 ± 0.06 and 0.89 ± 0.03 mg/ml, PE and PE-AuNPs can still be considered biocompatible. Nonetheless, our results suggest that the characteristics of recently produced nanoparticles can differ from those of the matching plant. Further investigation can provide a better understanding of the possible therapeutic and pharmacological impacts of PE-AuNPs.

Exploring the Complex Chemistry and Degradation of Ascorbic Acid in Aqueous Nanoparticle Synthesis.

Ascorbic acid (AA) is the most widely used reductant for noble metal nanoparticle (NP) synthesis. Despite the synthetic relevance, its aqueous chemistry remains misunderstood, due in part to various assumptions about its reduction pathway which are insufficiently supported by experimental evidence. This study aims to provide an understanding of the complex chemistry associated with AA under aqueous conditions. We demonstrate that (i) AA undergoes appreciable degradation in alkaline solution on a timescale relevant to NP synthesis, (ii) contrary to popular belief, AA does not degrade into dehydroascorbic acid (DHA), nor is DHA the oxidized product of AA under noble metal NP synthetic conditions, (iii) DHA, which readily degrades under alkaline conditions, can also effectively reduce metal salt precursors to metal NPs, (iv) neither ascorbate nor dehydroascorbate act as surface capping agents post-synthetically on the NPs (v) AA degradation time greatly affects the morphology and polydispersity of the resultant NP. Results from our mechanistic investigation enabled us to utilize purposefully-aged reductants to achieve control over shape yield and monodispersity in the seed-mediated synthesis of Au nanorods. Our findings have important implications for achieving monodispersed products in the many metal NP synthesis reactions that make use of AA as a reducing agent.

Exploring the Complex Chemistry and Degradation of Ascorbic Acid in Aqueous Nanoparticle Synthesis

Ascorbic acid (AA) is the most widely used reductant for noble metal nanoparticle (NP) synthesis. Despite the synthetic relevance, its aqueous chemistry remains misunderstood, due in part to various assumptions about its reduction pathway which are insufficiently supported by experimental evidence. This study aims to provide an understanding of the complex chemistry associated with AA under aqueous conditions. We demonstrate that (i) AA undergoes appreciable degradation in alkaline solution on a timescale relevant to NP synthesis, (ii) contrary to popular belief, AA does not degrade into dehydroascorbic acid (DHA), nor is DHA the oxidized product of AA under noble metal NP synthetic conditions, (iii) DHA, which readily degrades under alkaline conditions, can also effectively reduce metal salt precursors to metal NPs, (iv) neither ascorbate nor dehydroascorbate act as surface capping agents post‐synthetically on the NPs (v) AA degradation time greatly affects the morphology and polydispersity of the resultant NP. Results from our mechanistic investigation enabled us to utilize purposefully‐aged reductants to achieve control over shape yield and monodispersity in the seed‐mediated synthesis of Au nanorods. Our findings have important implications for achieving monodispersed products in the many metal NP synthesis reactions that make use of AA as a reducing agent.

Biogenic synthesis of metal nanoparticles: promoting green nanotechnology and sustainable development goals

Biogenic synthesis of metal nanoparticles: promoting green nanotechnology and sustainable development goals

Tuning the Selectivity of Catalytic Nitrile Hydrogenation with Phase-Controlled Co Nanoparticles Prepared by Hydrosilane-Assisted Method.

Cobalt (Co) is a promising candidate to replace noble metals in the hydrogenation process, which is widely employed in the chemical industry. Although the catalytic performance for this reaction has been considered to be significantly dependent on the Co crystal phase, no satisfactory systematic studies have been conducted, because it is difficult to synthesize metal nanoparticles that have different crystalline structures with similar sizes. Here we report a new method for the synthesis of cobalt nanoparticles using hydrosilane as a reducing agent (hydrosilane-assisted method). This new method uses 1,3-butanediol and propylene glycol to successfully prepare fcc and hcp cobalt nanoparticles, respectively. These two types of Co nanoparticles have similar sizes and surface areas. The hcp Co nanoparticles exhibit higher catalytic performance than fcc nanoparticles for the hydrogenation of benzonitrile under mild conditions. The present hcp Co catalyst is also effective for highly selective benzyl amine production from benzonitrile without ammonia addition, whereas many catalytic systems require ammonia addition for selective benzyl amine production. Mechanistic studies revealed that the fast formation of the primary amine and the prevention of condensation and secondary amine hydrogenation promote selective benzonitrile hydrogenation for benzylamine over hcp Co nanoparticles.

Development of AgNPs-PVP/TPU based flexible strain sensors for structural health monitoring of composite structures

Real-time in-stu structural health monitoring (SHM) of composite structure developed through highly sensitive and flexible smart sensors based on colloidal solution of Silver Nano Particles (AgNPs). Synthesis of AgNPs through chemical reduction method by citrate and then in Haxen phase transferred by using surfactant Cetyltrimethylammonium bromide (CTAB). Colloidal solution of AgNPs-Haxen and Polyvinylpyrrolidone (PVP) - Haxen has been followed by mixed, calcined and deposited that thick paste on flexible Thermoplastic Polyurethane (TPU) film. These sensors become more sensitive than metallic foil made sensors and farther this sensor pasted on polymer composite for monotonic loading like tensile loading. The data extracted from sensors was monitored effectively by data acquisitioning technique using Keithley KUSB-3100. This research based on chemical synthesis of metallic nanoparticles like silver, its functionalization, protection of these nanoparticles from environment by capping agents and by creating inert atmosphere respectively. Then these functionalized capped nanoparticles are embedded on the surface of thermoplastic Urethane (TPU) film to make piezo resistive semi conductive strips which serve as flexible strain gauge/smart sensor. One other technique is also being used to make sensor is that colloidal solution of metallic Nanoparticles sprays over TPU substrate using Connective Self Assembly (CSA) method. The sensor then properly attached to Glass fabric reinforced polymer (GFRP) composite and calibrated using data acquisitioning (DAQ) under different mode of testing.

Biosynthesis of Silver and Gold Nanoparticles Using Geum urbanum L. Rhizome Extracts and Their Biological Efficiency

AbstractThe present study evaluates the biosynthesis of AgNPs and AuNPs using aqueous and ethanolic Geum urbanum L. rhizome extracts. The biosynthesized metal nanoparticles (MNPs) were characterized using UV-Vis spectroscopy, FTIR, DLS, SEM, EDX, and TEM. The UV-Vis spectra confirmed the synthesis of AgNPs and AuNPs through peaks corresponding to the surface plasmon effect of metallic Ag (400–430 nm) and Au (530–570 nm). FTIR analysis indicated that alcohols, phenols, proteins, and carbohydrates from G. urbanum rhizome extracts composition are involved in MNPs synthesis. In DLS analysis, AgNPs (34.26–41.14 nm) showed smaller hydrodynamic diameters than AuNPs (46.26–70.29 nm). At the same time, all values for zeta potential were negative, between − 21 and − 13 mV, suggesting good stabilities for all the colloidal MNPs systems in dispersion. TEM analysis showed that the biosynthesized AgNPs had a spherical morphology, while AuNPs were quasi-spherical, polygonal, and triangular. According to TEM data, AgNPs synthesized using aqueous and ethanolic G. urbanum rhizome extracts were characterized by mean diameters of 9.82 ± 3.68 and 14.29 ± 3.46 nm, while AuNPs by 15.88 ± 6.28 and 24.89 ± 10.75 nm, respectively. EDX analysis confirmed the presence of metallic Ag and Au in the MNPs composition by detecting strong signals at 3 (AgNPs) and 2.2 keW (AuNPs). In disc diffusion assay, MNPs showed good antimicrobial activity against Gram-positive (S. aureus MSSA, S. aureus MRSA, S. epidermidis) and Gram-negative (E. coli, P. aeruginosa, K. pneumoniae) bacteria and yeasts (C. albicans). AgNPs and AuNPs were also characterized by a significant antioxidant potential, evaluated through in vitro assays (lipoxygenase inhibition, DPPH radical scavenging activity, metal ion chelating activity, and hydroxyl radical scavenging assays). An overall better activity was obtained for the ethanolic G. urbanum rhizome extract and its derived AgNPs (EC50 = 34.2 ± 1.86 mg/mL in lipoxygenase inhibition assay). Therefore, the G. urbanum rhizome extracts proved to be excellent sources for biologically active AgNPs and AuNPs.

An acoustofluidic picoinjector

Droplet microfluidics has emerged as a valuable technology for a multitude of chemical and biomedical applications, offering the capability to create independent microenvironments for high-throughput assays. Central to numerous droplet microfluidic applications is the picoinjection of materials into individual droplets, yet existing picoinjection methods often exhibit high power requirements, lack biocompatibility, and/or suffer from limited controllability. Here, we present an acoustofluidic picoinjector that generates acoustic pressure at the droplet interface to enable on-demand, energy-efficient, and biocompatible injection at high precision. We validate our platform by performing acid-base titrations by iteratively injecting picoliter volume reagents into droplets to induce pH transitions detectable by color change in solution. Additionally, we demonstrate the versatility of the acoustofluidic picoinjector in the synthesis of metallic nanoparticles, yielding highly monodisperse and reproducible particle morphologies compared to conventional bulk-phase techniques. By facilitating controlled delivery of reagents or biological samples with unparalleled accuracy, acoustofluidic picoinjection broadens the utility of droplet microfluidics for a myriad of applications in chemical and biological research.

Synthesis of Metallic and Metal Oxide Nanoparticles Using Homopolymers as Solid Templates: Luminescent Properties of the Eu+3 Nanoparticle Products

Starting from poly(4-vinylpyridine) ((P4VP)n), poly(2-vinylpyridine) ((P2VP)n), and [N=P(O2CH2CF3)]m-b-P2VP20 block copolymers, a series of metal-containing homopolymers, (P4VP)n⊕MXm, (P2VP)n⊕MXm, and [N=P(O2CH2CF3)]m-b-P2VP20]⊕MXm MXm = PtCl2, ZnCl2, and Eu(NO3)3, have been successfully prepared by using a direct and simple solution methodology. Solid-state pyrolysis of the prepared metal-containing polymeric precursors led to the formation of a variety of different metallic and metal oxide nanoparticles (Pt, ZnO, Eu2O3, and EuPO4) depending on the composition and nature of the polymeric template precursor. Thus, whereas Eu2O3 nanostructures were obtained from europium-containing homopolymers ((P4VP)n⊕MXm and (P2VP)n⊕MXm), EuPO4 nanostructures were achieved using phosphorus-containing block copolymer precursors, [N=P(O2CH2CF3)]m-b-P2VP20]⊕MXm with MXm = Eu(NO3)3. Importantly, and although both Eu2O3 and EuPO4 nanostructures exhibited a strong luminescence emission, these were strongly influenced by the nature and composition of the macromolecular metal-containing polymer template. Thus, for P2VP europium-containing homopolymers ((P4VP)n⊕MXm and (P2VP)n⊕MXm), the highest emission intensity corresponded to the lowest-molecular-weight homopolymer template, [P4VP(Eu(NO3)3]6000, whereas the opposite behavior was observed when block copolymer precursors, [N=P(O2CH2CF3)]m-b-P2VP20]⊕MXm MXm= Eu(NO3)3, were used (highest emission intensity corresponded to [N=P(O2CH2CF3)]100-b-[P2VP(Eu(NO3)3)x]20). The intensity ratio of the emission transitions: 5D0 → 7F2/5D0 → 7F1, suggested a different symmetry around the Eu3+ ions depending on the nature of the polymeric precursor, which also influenced the sizes of the prepared Pt°, ZnO, Eu2O3, and EuPO4 nanostructures.

Antimicrobial Activity of Green Synthesized Silver and Copper Oxide Nanoparticles against the Foodborne Pathogen Campylobacter jejuni.

Campylobacter jejuni is a major cause of global foodborne illnesses. To develop alternative antimicrobial strategies against C. jejuni, this study designed and optimized the green synthesis of metallic nanoparticles (NPs) with intracellular components of the medicinal fungus Ganoderma sessile to provide the needed reducing and stabilizing agents. NPs were characterized by transmission electron microscopy and dynamic light scattering, and the quasi-spherical NPs had sizes of 2.9 ± 0.9 nm for the copper oxide NPs and 14.7 ± 0.6 nm for the silver NPs. Surface charge assessment revealed zeta potentials of -21.0 ± 6.5 mV and -24.4 ± 7.9 mV for the copper oxide and silver NPs, respectively. The growth inhibition of C. jejuni by the NPs occurred through attachment to the outer cell membrane and subsequent intracellular internalization and resulted in minimum inhibitory concentrations of the silver NPs at 6 µg/mL and copper oxide NPs at 10 µg/mL. On the other hand, a differential ROS production caused by silver and copper NPs was observed. In summary, this research presents the first demonstration of using green synthesis with the medicinal fungus G. sessile to produce metallic NPs that effectively inhibit C. jejuni growth, providing a sustainable and effective approach to the traditional use of antimicrobials.

Green Synthesis of Metallic Nanoparticles from Quercus Bark Extracts: Characterization and Functional Properties.

Quercus species are utilized for their durable wood, providing sustenance for wildlife, conserving biodiversity, and contributing ecological, medicinal, and esthetic benefits to ecosystems and landscapes. In this study, we aimed to use the bark of three Quercus species (Q. dalechampi, Q. fraineto, and Q. petraea) for the synthesis of silver and gold nanoparticles (AgNPs and AuNPs). The aqueous extracts from the bark of Quercus sp. acted both as reducing and stabilizing agent, facilitating the rapid synthesis of AuNPs (AuQD, AuQF, and AuQP) and AgNPs (AgQD, AgQF, and AgQP). The obtained nanoparticles were characterized using UV-vis spectroscopy, TEM, DLS, and FTIR. Characterizations revealed that the nanoparticles exhibited a variety of shapes, such as polygonal, triangular, and spherical forms, with sizes ranging between 14 and 24 nm for AuNPs and 45-70 nm for AgNPs. The total phenolic content was assessed through spectroscopic methods, while several individual phenolic compounds were identified and quantified using UPLC-PDA. Furthermore, we assessed the antioxidant, antibacterial, and antifungal capacities of AuNPs, AgNPs, and raw extracts. The highest antioxidant activity was observed for raw extracts, followed by AgNPs and AuNPs, while the most potent antibacterial and antifungal activity was observed in AgQP. Moreover, cytotoxicity was examined in a human keratinocyte cell line (HaCaT). The results indicated no cytotoxic effects for AuNPs, while AgNPs and the raw extracts exhibited cytotoxic effects after 48 h of incubation. This research underscores the multifaceted utility of Quercus bark extracts in the green synthesis of metallic nanoparticles and their subsequent bioactivity assessment, suggesting promising perspectives for their application in various fields while urging cautious consideration of their cytotoxic implications.

Green synthesis of silver nanoparticles using Senna alexandrina leaf extracts and their antibacterial, larvicidal, nanotoxicity and photocatalytic activity

Biological synthesis of metal nanoparticles has been discovered in recent years, and they have been effectively manufactured and studied from diverse plant extracts. Recent research has shown that nanoparticles have extremely promising antibacterial, larvicidal and anticancer effects. The current study aimed to synthesize Senna alexandrina leaf extract-mediated silver nanoparticles (SA-AgNPs) as are reducing and capping agent. The produced SA-AgNPs were characterized by using UV–visible spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and Field emission scanning electron microscopy with energy dispersive spectroscopy (FESEM-EDS). The result showed synthesized SA-AgNPs were confirmed by UV–visible spectroscopy with 440 nm absorption. FT-IR analysis shows the presence of phosphine, primary amines, carboxylic acids, ether, and alkyl halides biomolecules in both plant extract and SA-AgNPs. XRD findings revealed the crystalline structures of produced SA-AgNPs. The spherical shape of SA-AgNPs with an average size of 20–35 nm was confirmed using FESEM. The SA-AgNPs show better antibacterial activity against E. coli (18.0 ± 0.25 mm), S. aureus (17.2 ± 0.36 mm), P. aeruginosa (16.8 ± 0.12 mm), and leaf extract of S. alexandrina showed minimal antibacterial activity. The SA-AgNPs show 100 % mortality for both Cx. quinquefasciatus and Ae. aegypti after 48 hrs. The brine shrimp lethal assay of the SA-AgNPs shows 100 % at 30 µg after 24 hrs of brine shrimp which indicated the presence of cytotoxicity this suggests that produced SA-AgNPs are slightly toxic. The photocatalytic activity was also tested using reactive orange 16 (RO16) and phenol red (PR) with the percentage of degradation being about 93.95 % and 92.91 % respectively. These results suggest that biosynthesized SA-AgNPs have promising properties that can be used as an effective biomedical and environmental protectant.

Lignin: A multifunctional and sustainable photothermal material for solar-driven thermoelectric generation and desalination

The abundant aromatic ring structure and a large number of oxygen-containing functional groups in the lignin offer the possibility of achieving excellent photothermal conversion ability and modulating the synthesis of metal nanoparticles. Herein, three kinds of the lignin with different functional group content were employed to investigate the potential influence on the particle size and the solution stability of the CuS through two reaction pathways. The result of various characterizations indicated that the higher the oxygen-containing functional group content (4.83 mmol/g) of lignin, the smaller the size of CuS nanoparticles (∼80 nm) in solution. And the smaller and homogeneously dispersed CuS offered a higher surface temperature for the solar-driven heat-generating materials. The regulation mechanism was also proposed based on the result of the molecular dynamics simulation and DFT calculation. Subsequently, the photothermal film (Route2 DTAL-PVA-30) and solar-driven aerogel evaporator (Route2 DTAL-AG3) were successfully prepared using the lignin-guided stabilization solution of CuS nanoparticles. The photothermal conversion efficiency of 49.43 % and the equilibrium voltage of 266 mV can be achieved by the Route2 DTAL-PVA-30 under 1 sun using a thermoelectric generator. The Route2 DTAL-AG3 exhibited promising salt-rejecting property and outstanding acid and alkali resistance performance, reaching an evaporation rate of up to 1.93 kg/(m2 h) in the 3.5 wt% seawater under 1sun. This work may provide a novel strategy to realize the regulatory role of lignin in the metal synthesis and achieve the high value-added applications of the lignin.

Bespoke Metal Nanoparticle Synthesis at Room Temperature and Discovery of Chemical Knowledge on Nanoparticle Growth via Autonomous Experimentations (Adv. Funct. Mater. 27/2024)

Bespoke Metal Nanoparticle Synthesis at Room Temperature and Discovery of Chemical Knowledge on Nanoparticle Growth via Autonomous Experimentations (Adv. Funct. Mater. 27/2024)

Antioxidant, antiglycation, and antibacterial of copper oxide nanoparticles synthesized using Caesalpinia Sappan extract.

Synthesis of metal nanoparticles using plant extracts is environmentally friendly and of increasing interest. However, not all plant extracts can meet successfully on the synthesis. Therefore, searching for the high potential extracts that can reduce the metal salt precursor in the synthesis reaction is essential. The present study explores the synthesis of copper oxide nanoparticles (CuONPs) using Caesalpinia sappan heartwood extract. Phytochemical analysis and determination of the total phenolic content of the extract were performed before use as a reducing agent. Under the suitable synthesized condition, a color change in the color of the solutions to brown confirmed the formation of CuONPs. The obtained CuONPs were confirmed using ultraviolet-visible spectroscopy, photon correlation spectroscopy, X-ray diffraction, scanning electron microscope, energy dispersive X-ray, and Fourier transform infrared analysis. The synthesized CuONPs investigated for antioxidant, antiglycation, and antibacterial activities. CuONPs possessed antioxidant activities by quenching free radicals with an IC50 value of 63.35 µg/mL and reducing activity with an EC range of 3.19-10.27 mM/mg. CuONPs also inhibited the formation of advanced glycation end products in the bovine serum albumin/ribose model with an IC50 value of 17.05 µg/mL. In addition, CuONPs showed inhibition of human pathogens, including Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, and prevention of biofilm formation and biofilm eradication, with maximum inhibition of approx. 75%. Our findings suggest that C. sappan extract can be used to obtain highly bioactive CuONPs for the development of certain medical devices and therapeutic agents.

METHODS OF BIOSYNTHESIS OF METAL NANOPARTICLES, PROSPECTS OF APPLICATION IN CROP PRODUCTION

The main objective of this review is to consider the environmentally ecological synthesis of nanoparticles with the help o f plants and the importance of this approach, application areas. It can be said that metal nanoparticles take place in all spheres of human life, such as food security, medicine, veterinary medicine, agriculture, environmental protection, energy, electronics. Currently, the development of environmentally friendly methods for the chemical and biological synthesis of metal nanoparticles is a pressing issue attracting significant attention from scientists worldwide. In the biological synthesis of metals, various living organisms, fungi, algae, and plants can be used. And the importance of using these nanoparticles in crop production is still being actively studied. In our work, we reviewed articles by scientists from a number of countries who have widely used this method in various industries. The biocompatibility and stability of metal nanoparticles produced through "green synthesis" have been demonstrated in numerous studies. A thorough literature review also examined the plants used in this synthesis process and the various applications of the synthesized metal nanoparticles based on their properties. Tһe topic of this revew is one of the relevant for Kazakhstan, therefore, the prospects of using metal nanoparticles in agricultural crop production and as growth stimulants and in plant protection are being considered in the country.

Antifungal screening of silver nanoparticles biosynthesized by Aliinostoc oryzae against plant pathogenic fungi

Metallic nanoparticles exhibit exceptional antifungal characteristics and are regarded as a feasible substitute for the control of diverse fungus species. Cyanobacteria have received significant recognition as nanobiofactories across all identified taxa owing to their remarkable ability to assimilate toxins from their environment. Consequently, cyanobacteria-mediated metal nanoparticle synthesis represents an innovative strategy for biological regulation. The present investigation assessed the effectiveness of silver nanoparticles (AgNPs) manufactured using Iranian cyanobacteria, Aliinostoc oryzae, as fungus inhibitors against plant pathogens. For this purpose, the cyanobacterial strain was cultured in BG-110, medium and AgNPs were synthesized by the wet biomass method. The AgNPs were then characterized by UV–visible spectroscopy, DLS, zeta potential, field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction tests. Afterwards, the antifungal activities of fabricated nanoparticles were tested against fungal strains of Botrytis cinerea, Alternaria alternate, Colletotrichum gloeosporioides, Fusarium oxysporum, Phytophthora capsici, Pythium ultimum, and Rhizopus stolonifera. The results of UV–vis spectrophotometry confirmed the AgNP formation with a color change to dark brown at a wavelength range of 430–432 nm. Morphological examination through the Field Emission Scanning Electron Microscope (FESEM) indicated irregular and spherical shapes. X-ray diffraction (XRD) results showed a cubic crystalline structure with a crystallite size of approximately 20 nm. The zeta potential and electrophoretic mobility of the nanoparticles were −33.67 mV and 0.35 Vs/cm2, respectively. Fourier-transform infrared spectroscopy (FTIR) analysis identified a sharp and intense peak at 538 cm−1, corresponding to the stretching vibration of silver nanoparticle bonds. Based on the antifungal activity results, Pythium ultimum had the largest growth inhibition zone. On the other hand, Colletotrichum gloeosporioides and Alternaria alternate had the smallest inhibition zones. These findings demonstrate the ability to characterize and test AgNPs produced by Iranian cyanobacteria for their antifungal activity.

In-situ modification of nickel electrode by coupling the microbial corrosion and microbial reduction using Shewanella oneidensis for enhanced electrocatalysis

Shewanella oneidensis is a facultative anaerobe with the ability to use different terminal electron donors and acceptors. Therefore, S. oneidensis can be used either as an oxidizing agent for microbial corrosion of metals or as a reducing agent for microbial synthesis of metal nanoparticles depending on the metal type. Herein, we have shown that S. oneidensis MR-1 can be used for both microbial corrosion of nickel foam (NF) and microbial synthesis of Ni nanoparticles under environmentally benign conditions. It is found that S. oneidensis MR-1 can accelerate the corrosion process to form metal hydroxides on the surface of NF in the presence of Fe3+, and the obtained electrode shows improved electrocatalytic activity toward oxygen evolution reaction with an overpotential of 0.265 V to achieve a current density of 10 mA cm−2. However, the corrosion process of NF by S. oneidensis MR-1 is severely inhibited in the presence of Fe2+. In addition, aside from the corrosion process of NF, we have for the first time shown that Ni nanoparticles can be synthesized by the reduction of Ni2+ ions using S. oneidensis MR-1. The results show that the microbial energy metabolism of S. oneidensis MR-1 facilitates the electron transfer from electron-donating NF to the electron-accepting metal ions (Fe3+, Ni2+) across the microbes, coupling the corrosion process (Ni → Ni2+) and metal ions reductions (Fe3+ → Fe2+, Ni2+ → Ni), which demonstrates great potential for in-situ modification of electrode with microorganism and provides new avenue for electrode fabrication.

Study on Synthesis and Characterization of Metal Nanoparticles for Biomedical Applications

In this research paper, I have thoroughly described about the topic “Study on Synthesis and Characterization of Metal Nanoparticles for Biomedical Applications.” Metal nanoparticles have emerged as promising candidates for a myriad of biomedical applications due to their unique physicochemical properties, offering a wide array of opportunities for innovation in healthcare. This abstract discusses metal nanoparticle creation, characterization, and biomedical applications. Chemical reduction, green synthesis, physical deposition, and biological methods allow fine nanoparticle size, shape, and composition control for biomedical applications. TEM, DLS, XRD, UV-Vis, FTIR, SEM, and TGA reveal metal nanoparticles' structural, chemical, and optical properties. Metal nanoparticles are used in medication delivery, imaging contrast, targeted therapy, and diagnostics. Their small size, large surface area-to-volume ratio, and tunable optical properties make them suitable for drug delivery, where they can encapsulate and release therapeutic substances at precise body regions. Metal nanoparticles also improve illness identification and monitoring in MRI, CT, and fluorescence imaging by acting as contrast agents. They provide innovative cancer and microbial infection treatments due to their photothermal and antibacterial characteristics. Metal nanoparticles also find utility in biosensing applications, facilitating the detection of biomolecules and disease biomarkers with high sensitivity and specificity. Overall, the synthesis and characterization of metal nanoparticles represent a vibrant area of research with significant implications for advancing healthcare technologies, offering versatile platforms for addressing key challenges in diagnostics, therapeutics, and imaging in biomedicine.